This invention relates to a method and an apparatus for thermally killing weeds.
The use of chemical herbicides to kill weeds has come under increasing attack as being environmentally unfriendly.
A number of alternative ways of killing weeds have been suggested.
Thermal killing of weeds has achieved some measure of success as an alternative to the use of herbicides. Some such devices burn propane or other gaseous or liquid hydrocarbons to produce flames or hot air aimed directly at the weeds. See, for example, the devices described in U.S. Pat. No. 5,020,510 and 5,189,832. One of the problems associated with this approach is setting fire to the weeds, which generates air pollution and, possibly, wild fires.
It has also been suggested to use hot foams to kill weeds. See, for example, U.S. Pat. No. 5,575,111.
It has been further suggested to spray hot water on weeds followed by compressing the sprayed weeds or applying a foam blanket to the sprayed weeds, the purpose of both approaches being to hold the hot water against the plants for an extended period of time. See, for example, U.S. Pat. Nos. 5,430,970 and 5,433,758.
It is an object of this invention to provide a method and apparatus for thermally killing weeds that is effective, economical, and minimizes the potential for inadvertently causing fires.
The invention is a method and apparatus for thermally killing weeds, grasses, or other unwanted vegetation adjacent auto or rail roadways, airport runways, or any area where it is desired to remove such unwanted vegetation.
The method of this invention for thermally killing weeds involves first applying water at ambient temperature onto the weeds targeted to be eliminated and subsequently heating the water and the weeds to a temperature sufficient to cause bursting of cell walls and denaturing of plant proteins which results in the death of the exposed tops of the weeds.
The apparatus for thermally killing weeds comprises a water spray unit and an associated heater enclosure or box located in trailing relationship to the heater. The heater box has a top or roof, side walls, and end walls. The bottom of the heater box is open to the atmosphere. The heater box has an infrared heat generating element located on the underside of the roof. The infrared heat generating element may be corrugated or otherwise shaped to provide maximum exposure of the weeds to infrared heating. The open bottom of the heater box is, in operation, located close to ground level, and has a porous apron extending from the bottom of the heater box into contact with the ground.